Samarium

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Promethium – Samarium – Europium
Sm Pu
	\n Full table

General

Name, Symbol, Number

Samarium, Sm, 62

Chemical series

Lanthanides

Group, Period, Block

_ , 6 , f

Density, Hardness

7353 kg/m³, no data

Appearance

silvery white

Atomic properties

Atomic weight

150.36(3) amu

Atomic radius (calc.)

185 (238) pm

Covalent radius

no data

van der Waals radius

no data

Electron configuration

[Xe]66 s²4f⁶

e^- 's per energy level

2, 8, 18, 24, 8, 2

Oxidation states (Oxide)

3 (mildly basic)

Crystal structure

Rhombohedral

Physical properties

State of matter

solid (__)

Melting point

1345 K (1962 �F)

Boiling point

2076 K (3277 �F)

Molar volume

19.98 ×1010^-6 m³/mol

Heat of vaporization

166.4 kJ/mol

Heat of fusion

8.63 kJ/mol

Vapor pressure

563 Pa at 1345 K

Velocity of sound

2130 m/s at 293.15 K

Miscellaneous

Electronegativity

1.17 (Pauling scale)

Specific heat capacity

200 J/(kg*K)

Electrical conductivity

0.956 10⁶/m ohm

Thermal conductivity

13.3 W/(m*K)

1^st ionization potential

544.5 kJ/mol

2^nd ionization potential

1070 kJ/mol

3^rd ionization potential

2260 kJ/mol

4^th ionization potential

3990 kJ/mol

Most stable isotopes

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n

iso	NA	half-life	DM	DE M eV	DP
¹⁴⁴Sm	3.07%	¹⁴⁴Sm is stable with 82 neutrons
¹⁴⁶Sm	{syn.}	1.03E+8 y	&alpha	2.529	¹⁴²Nd
¹⁴⁷Sm	14.99%	1.06E+11 y	α	2.310	¹⁴³Nd
¹⁴⁸Sm	11.24%	7E+15 y	α	1.986	¹⁴⁴Nd
¹⁴⁹Sm	13.82%	>2E+15 y	α	no data	¹⁴⁵Nd
¹⁵⁰Sm	7.38%	¹⁵⁰Sm is stable with 88 neutrons
¹⁵²Sm	26.75%	¹⁵⁰Sm is stable with 90 neutrons
¹⁵⁴Sm	22.75%	¹⁵⁰Sm is stable with 92 neutrons

SI units & STP are used except where noted.

Samarium is a chemical element in the periodic table that has the symbol Sm and atomic number 62.

Table of contents

1 Notable characteristics
2 Applications
3 History
4 Biological role
5 Occurrence
6 Compounds
7 Isotopes
8 Precautions
9 Reference
10 External links

Notable characteristics

\nSamarium is a rare earth metal, with a bright silver lustre, that is reasonably stable in air; it ignites in air at 150�C. Three crystal modifications of the metal also exist, with transformations at 734 and 922�C, respectively.

Applications

\nUses of Samarium include:

Carbon-arc lighting for the motion picture industry (together with other rare earth metals). \n* Doping CaF₂ crystals for use in optical masers or lasers.\n* As a neutron absorber in nuclear reactors.\n* For alloys and headphones.\n* Samarium-Cobalt magnets; SmCo₅ is used in making a new permanent magnet material with the highest resistance to demagnetization of any known material, and an intrinsic coercive force as high as 2200 kA/m. \n* Samarium oxide is used in optical glass to absorb infrared light. \n* Samarium compounds act as sensitizers for phosphors excited in the infrared.\n* Samarium oxide is catalytic for the dehydration and dehydrogenation of ethanol.

History

\nSamarium was first discovered spectroscopically in 1853 by swiss chemist Jean Charles Galissard de Marignac by its sharp absorption lines in didymium, and isolated in Paris in 1879 by french chemist Paul Émile Lecoq de Boisbaudran from the mineral samarskite ((Y,Ce,U,Fe)₃(Nb,Ta,Ti)₅O₁₆). Like the mineral, it was named after a Russian mine official, Colonel Samarski.

Biological role

\nSamarium has no known biological role, but is said to stimulate the metabolism.

Occurrence

\nSamarium is never found free in nature, but, like other rare earth elements, is contained in many minerals, including monazite, bastnasite and samarskite; monazite (in which it occurs up to an extent of 2.8%) and bastnasite are also used as commercial sources. Misch metal containing about 1% of Samarium has long been used, but it was not until recent years that relatively pure Samarium has been isolated through ion-exchange processes, solvent extraction techniques, and electrochemical deposition. Samarium can also be obtained by reducing its oxide with Lanthanum.

Compounds

\nCompounds of Samarium include:

Fluorides\n** SmF₂\n** SmF₃\n* Chlorides\n** SmCl₂\n** SmCl₃\n* Bromides\n** SmBr₂\n** SmBr₃\n* Iodides\n** SmI₂\n** SmI₃\n* Oxides\n** Sm₂O₃\n* Sulfides\n** Sm₂S₃\n* Selenides\n** Sm₂Se₃\n* Tellurides\n** Sm₂Te₃

Isotopes

\nNaturally occurring Samarium is composed of 4 stable isotopes, 144-Sm, 150-Sm, 152-Sm and 154-Sm, and 3 radioisotopes, 147-Sm, 148-Sm and 149-Sm, with 152-Sm being the most abundant (26.75% natural abundance). 32 radioisotopes have been characterized, with the most stable being 148-Sm with a half-life of 7E+15 years, 149-Sm with a half-life of more than 2E+15 years, and 147-Sm with a half-life of 1.06E+11 years. All of the remaining radioactive isotopes have half-lifes that are less than 1.04E+8 years, and the majority of these have half lifes that are less than 48 seconds. This element also has 5 meta states with the most stable being 141m-Sm (t_� 22.6 minutes), 143m1-Sm (t_� 66 seconds) and 139m-Sm (t_� 10.7 seconds). The primary decay mode before the most abundant stable isotope, 152-Sm, is electron capture, and the primary mode after is beta minus decay. The primary decay products before 152-Sm are element Pm (Promethium) isotopes, and the primary products after are element Eu (Europium) isotopes.